Miniature fans have very small dimensions. For example:                fans of the ebm-papst 250 series have dimensions of 8×25×25 mm;        those of the ebm-papst 400F series, 10×40×40 mm;        those of the ebm-papst 400 series, 20×40×40 mm; and        those of the ebm-papst 600 series, 25.4×60×60 mm.        
The power consumption of such fans is 0.4-0.6 W for the 250 series, 0.7-0.9 W for the 400F series, and 0.9-1.6 W for the 400 and 600 series. Their typical weight is approximately in the range from 4 to 35 grams.
Electronic devices today are being equipped with more and more functions and installed in smaller and smaller housings. This causes an increase in waste heat in the electronic circuit of such a device. One particular problem arises from the fact that in such a circuit, individual elements become particularly hot, e.g. power semiconductors, microprocessors, resistors with which a motor current is measured, etc. These particularly hot elements generate on the circuit board so-called “hot spots,” a term borrowed from geology: Iceland, for example, has many hot spring and geysers, i.e. many hot spots.
Cooling such hot spots with ordinary equipment fans is inefficient, since equipment fans such as those used, for example, in computers generate a relatively diffuse air flow that removes sufficient heat from the housing, but does not allow targeted cooling of individual hot spots.